Gray hair linked to immune system activity and viral infection

Gray hair linked to immune system activity and viral infection

In a recent study, researchers examined that why some people’s hair may turn gray in response to a serious illness or chronic stress.

Researchers at the National Institutes of Health and the University of Alabama, Birmingham have discovered a connection between the genes that contribute to hair color and the genes that notify our bodies of a pathogenic infection.

When a body is under attack from a virus or bacteria, the innate immune system kicks into gear.

All cells have the ability to detect foreign invaders and they respond by producing signaling molecules called interferons.

Interferons signal to other cells to take action by turning on the expression of genes that inhibit viral replication, activate immune effector cells, and increase host defenses.

The connection between hair pigmentation and innate immune regulation was initially a bit surprising.

The researchers are interested in genes that affect how our stem cells are maintained over time. They like to study gray hair because it’s an easy read-out of melanocyte stem cell dysfunction.

Melanocyte stem cells are essential to hair color as they produce the melanocytes that are responsible for making and depositing pigment into the hair shaft.

In this case, an unexpected link was found between gray hair, the transcription factor MITF, and innate immunity.

MITF is best known for its role in regulating the many functions within melanocytes.

But the researchers found that MITF also serves to keep the melanocytes’ interferon response in check. If MITF’s control of the interferon response is lost in melanocyte stem cells, hair-graying results.

Furthermore, if innate immune signaling is artificially activated in mice that are predisposed for getting gray hair, increased numbers of gray hairs are also produced.

Their discovery suggests that genes that control pigment in hair and skin also work to control the innate immune system.

These results may enhance scientists’ understanding of hair graying.

More importantly, discovering this connection will help us understand pigmentation diseases with innate immune system involvement like vitiligo.

Vitiligo, which causes discolored skin patches, affects between 0.5 percent to 1 percent of all humans.

Why mice that are predisposed for getting gray hair are more susceptible to dysregulated innate immune signaling needs more research to answer.

Melissa Harris is the primary author and assistant professor within the Department of Biology at UAB. William Pavan is a study co-author.

The study is published in the open access journal PLOS Biology.

Source: Public Library of Science.